This paper describes tensile performances of the optical fiber with a fracture origin. Three kinds of blade（steel round blade，steel flat blade，and diamond blade）are used make a fracture origin. Tensile tests of optical fiber with a fracture origin are carried out not only in air but also in water, salt water，ethyl alcohol, water glass，and machine oil，using a vertical tensile tester. Tensile speed is set to be 0.1，0.5，and 1.0 mm/min., respectively. It is found that the tensile strength distributions of optical fibers with fracture origins show Weibull distributions，and average value of tensile strength and shape parameter mon Weibull distribution have different values depending on used blade kinds. It is also clarified that tensile strengths decrease when optical fibers are cleaved in water，saltwater, and water glass while they increase in ethyl alcohol, and machine oil. Mirror end surfaces are easily obtained by making tensile strength low.

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The EMTP is widely used for lightning surge analysis. As for transmission lines，lightning outage of a transmission line has been studied. In the analysis, grounding resistance of a tower is usually modeled as a constant resistance model，however，it is known that soil ionization sometimes occurs by high currents such as a lightning stroke. Therefore the authors have developed grounding resistance models with soil ionization characteristics and investigated the effect of the models. In this paper，the authors analyzed three outages of existing 500kV transmission lines and compared a linear resistance model with a nonlinear model considering the soil ionization characteristics. The results suggest that a nonlinear model can be applied in the cases where the initial grounding resistance is relatively high.

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